High-performance raster scan CRT displays require high resolution rasters. In order to provide a high resolution raster display, the beam must be deflected rapidly across the screen of the CRT. As the speed requirement increases, the resistive losses of the deflecton coils increase because of "skin effect." This increase in loss can be minimized, but not eliminated, by the use of Litzendraht (litz) wire in these coils. Moreover, as the frequencies increase, the deflection yoke core, typically a powdered ferrite material, itself begins to heat up due to the material loss at high energy and high frequency.
Previous attempts to improve deflection yoke performance in CRT displays have included elements to sense the temperature of the deflection yoke and compensate or adjust the deflection circuit in response thereto. However, since this does not reduce the temperature of the deflection yoke, this technique provides no improvement on the ultimate power which may be provided to the deflection yoke.
Other more drastic techniques evade the problem by scanning with as many as eight separate controlled electron beam paths, reducing the number of scan lines and therefore scan deflection rate. However, this technique incurs an extreme economic penalty and redundant CRT electron gun driving and data separation circuitry.
Therefore, the present state of the art fails to provide any techniques for reducing the temperature of the deflection yoke, and further fails to appreciate the problems underlying the heat buildup in the deflection yoke.